This invention relates to a bicycle, and in particular to a bicycle in which forward movement may be generated not only by conventional rotation of the pedals, but also or alternatively by means of vertical reciprocal movement of the saddle.
In a conventional bicycle, a drive wheel is adapted to be driven in rotation by means of a gear wheel, an endless driving chain and a driving gear wheel. The driving gear wheel is rotatable by means of two cranks having pedals rotatably mounted thereon, the two cranks being mounted in opposition to one another. In use a user may sit on a saddle of the bicycle and apply a force first to one pedal and then to the other and effect rotation of the two cranks and thus of the driving gear wheel.
In my earlier patent application GB 2111924A there is described a bicycle wherein rotation of the drive wheel can be effected by the application of a force alternately to a pedal and to the saddle. The bicycle comprises a saddle mounted on a crossbar, and a force transmission member for transmitting a force from the cross bar to the pedal cranks. FIG. 1 is a perspective view of this arrangement in which saddle 1 is mounted at one end of crossbar 2, and force transmission member 3 is fixed to the crossbar 2 at a point substantially half way along its length.
As can be seen from FIG. 1 the triangular frame 4 of the bicycle is a double frame comprising pairs of spaced parallel elements. The force transmission member 3 is located between these frame elements, and in particular between the two paired elements 5 comprising the upper side of the frame triangle and two paired elements 6 forming the rearmost side of the triangle.
This double frame arrangement has a number of disadvantages. As can be seen from FIG. 1 there is no seat post. In a conventional bicycle fitted with derailleur gears a part of the gear mechanism is fitted to the seat post. The absence of a seat post in the arrangement of GB 2111924A makes the use of such gearing harder and more difficult and the number of gears available to a rider is substantially limited. A further disadvantage is that the bottom of the force transmission member 3 must be fitted to a one-piece crank 7. Since this crank is formed as a one-piece structure as a practical manufacturing question is not possible to provide an adequate bearing between the crank 7 and the force transmission member 3. A further disadvantage of this arrangement is the added manufacturing complexity and cost that is involved because it is difficult to adapt simply an existing bicycle production line to the manufacture of such double-framed bicycles. The cycle requires a large number of specially designed parts and components and does not make maximum use of the various standard cycle components that are available. Inevitably this increases cost further.
According to the present invention there is provided a cycle comprising, a pair of crank means, a drive wheel rotatable in response to rotation of the crank means, a pair of pedals for effecting rotation of respective crank means, and a seat post on which a saddle is mounted at one end, said seat post being connected to two transmission levers arranged respectively on either side of a cycle frame, whereby said cycle may be propelled either by rotation of said pedals or by a reciprocating movement of said seat post.
This arrangement overcomes or at least mitigates the aforementioned disadvantages. A seat post is provided to facilitate the provision of a greater number of gears. The transmission levers may extend vertically as far as the saddle itself and may even be connected directly thereto, in a preferred embodiment however the seat post is provided with a bifurcated lower portion forming two arms that are connected to the two transmission levers. This connection of the bifurcated arms of the seat post to the transmission levers is such that proper bearings may be provided, and the overall manufacturing complexity and costs are reduced.
In a particularly preferred arrangement the cycle frame comprises an upright member extending from the drive wheel axle, and a gear adjusting mechanism may be provided on the upright member adjacent the drive wheel. The cycle frame may still further comprise a rear wheel support member a part of which extends from the upright member to a steering post, and may further comprise a crossbar extending from the seat post and rotatably mounted to the steering post, and a bifurcated pair of reinforcing arms extending from an end of the crossbar adjacent the steering post no lower ends of the bifurcated arms of the seat post.
Viewed from another aspect the present invention provides a cycle comprising, a pair of crank means, a drive wheel rotatable in response to rotation of the crank means, a pair of pedals for effecting rotation of respective crank means, and a pair or handlebars on a steering post, wherein said cycle further comprises a first fixed frame portion including an upright member extending from the axle bearing of said drive wheel and a rear wheel support member extending between an upper end of said upright member and said steering post, and a second movable frame portion comprising a seat post connected to a pair of transmission levers and a crossbar extending from an upper part of said seat post to said steering post and being rotatably mounted thereto, said first frame portion being received within said second frame portion.
The first frame portion may further comprise a bar extending from said axle bearing to said steering post to form a triangle with said upright member and said rear wheel support member, and said second frame portion may further comprise a bifurcated reinforcing bar extending from said crossbar to lower ends of said bifurcated seat post arms.